It is demonstrated that ionization structure of NGC 7027 cannot be explained by static models based on the standard photoionization theory unless some complementary physical process is included. The main discrepancies are successfully eliminated by including charge transfer reactions with hydrogen for the following ions: C+, C+3, N+2, O+2, Ne+2, S+ and S+3, the rate coefficients being probably of the order of or larger than 10−9cm+3s−1 except for C+ and Ne+2; in addition the charge exchange rate for N+ is probably ∼200 times smaller than the value proposed by Steigman et al. (1971).